This invention relates to a ternary block copolymer in which poly A, poly B and poly C which are the polymers of monomers A, B and C are linked into a molecular chain in such a manner as "poly A-poly B-poly C" or "poly A-poly B-poly C-poly B-poly A" to have the poly A, the poly B and the poly C included in the molecular chain.
Heretofore, in efforts to improve physical properties of high polymer materials, blending of macromolecules of different kinds and random copolymerization, graft copolymerization and block copolymerization of monomers of different kinds have been attempted. It has been known that block copolymers of an unique micro-phase separated structure have novel properties because of their heterogeneous micro-structure. For example, ABA type block copolymers consisting of styrene and butadiene have already been marketed as thermoplastic rubber.
When a molecular chain formed with macro-molecules of different kinds are joined together, the component macro-molecular segments of different kinds do not intermix with each other. Meanwhile, since they are within the same molecular chain, they are restrained from phasic parting in distance and shape and thus form a structure having separated micro phases which are close to the size of a molecule. In the case of the commercially available ABA type block copolymers (A representing polystyrene and B polybutadiene) which are mentioned in the foregoing, it is well known that a block copolymer which includes 5% by weight or thereabout of styrene has polystyrene portion thereof from a spherical micro-domain measuring several hundred angstroms in diameter while the polybutadiene portion is in a continuous phase filling up a space between the spherical domains of polystyrene.